I've used it in my rover, titan, excursion, and mercedes diesel for about a decade and my only cat failure was on the Rover... hmm... but I had a bad head gasket leak at the time.

Abran, Alex and others may be the best source but the three rover engines I have opened (a couple repeatdedly) looked new with rotella after more than a hundred thousand miles. Ditto for the Mercedes. The one rover engine that I opened with regular dealer changes looked like a dirty diaper inside.

 

What is "it?" Which oil have you used?

 

ZDDP , (zinc/phos) is not a cleaning agent,!!
It's added to oil as extreme pressure wear protection , and it came about 1950's with low contents in oils , and eventually got to about (1000ppm to 1300ppm) early 70's,, (for most gasoline engine oils).
(ppm=part per million),,
Diesel oils always had a little more ZDDP compared to gasoline engine oils,,
But ZDDP is not responsible for cleaning inside of an engine by itself,,!!
And now there is a debate that there are newer extreme pressure agents , than ZDDP,
That being said , I personally wouldn't take a chance using newer oils (with lower than 1000ppm ZDDP) on flat tappet pushrods engines ,
(but I do use newer better oils for newer design overhead cam engines)

So if an oil does a good job cleaning inside an engine,, it doesn't necessarily mean that it also did a good job of lubricating !!!
Good lubrication of different parts , is the. Job of good base oil formula NOT ZDDP content by itself,,!!
So for our Rover engines, you want a good base oil that has min of 1000ppm ZDDP, and change it frequently,,,
Keep in mind all synthetic oils are inharantly cleaning engine surfaces,
But,, it doesn't mean all synthetics are equal in lubrication, ( there is a big difference in lubrication capability of diff. synt. oils from diff brands, also big difference in diff. Products/weights. from same brand,!!!)
Also ,, there are some conventional oils that are better than a lot of more expensive synt oils, as far as wear lubrication is concerned,!!
((There are very few exceptions,)) but in general, most diesel oils are not as good as, best gasoline engine oils...
just because an oil provides adecuite protection in an engine, doesnt mean it's the best oil, But that it is just "good enough" to do that job, and when something bad happens (over heating/lack of oil high pressure/etc,,, most people don't realize maybe if they had best oil for that application, it might have saved the day,,
By the way a very, very expensive oil , doesn't always mean the best ,!!
There are so many lower priced products , that will outperform , highest priced , hyped up, products,..

 

Rotella 15w40.